Method of producing noncrystalline explosive azide



Patented June 20, 1933 UNITED STATES WILLIAM H. RINKENBACH, F DOVER, NEW JERSEY METHOD OF PRODUCING NONCRYSTALLINE EXILO SIVE AZIDE No Drawing.

Application filed March 10, 1931. Serial No. 521,517.

(GRANTED UNDER THE AOT OF MARCH 3, 1883, AS AMENDED APRIL 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Govern ment for governmental purposes, without the payment to me of any royalty thereon.

The subject of this invention is a method of preparing non-crystalline lead azide.

The main object of the invention is the production of lead azide in the form of a colloidal mass thereby making the same safe to handle and producing a form of lead azide readily available for use in detonators I The value of lead azide as an initlator (detonator) has been recognized for many years and it has been used for this purpose to some extent. However, this compound, as usually prepared and as reported in the literature, is a crystalline material. Fur thermore it has been recognized and noted that the sensitivity is dependent upon crystal size, this sensitivity being so great as to render the handling of the material extremely dangerous if the crystals exceeded certain sizes. Efforts to make the manufacture and use of lead azide reasonably safe have taken the direction of establishing conditions which would control the crystal size of the product within certain limits.

I have discovered that it is possible to prepare lead azide as well as other azides such as those of silver, and mercury, in such a manner that the product will have a noncrystalline structure, being composed ofaggregates of colloidal particles. The colloidal particles consist of roughly spherical particles approximately 0.0001 inch 1n diameter. The aggregate of these are irregular in size and shape and have no regular structure. V

The usual method of preparing crystalline lead azide has been to add a 2% dilute solution of sodium azide to a 5% dilute solution of lead acetate or lead nitrate, while agitating the solution being added to. The usual time of mixing has been two hours.

I have found that by altering the concentrations, order, and time of mixing, a noncrystalline material can be precipitated; and that this can be separated, washed, and dried in the usual manner, I have found that more concentrated solutions than those reported in the literature are preferable, that the addimetallic salt dissolved in sufficient water to tion of the solution of lead acetate or nitrate to the sodium azide solution is preferable, and the time of mixing should be made very short so as .to prevent the formation and p growth of crystalline lead azide.

As an xample of the application of my process, the following is given as an illustration, although it is not to be implied that the method is limited to the use of the concentrations given, nor is it absolutely necessary that 6 the solution of the lead salt be'added to the solution of azide.

An aqueous solution containing 4 percent of sodium azide is maintained at a te'mperap ture preferably not higher than 25 0., 6 while being agitated. To this is added a slight excess of lead nitrate or of lead acetate which has been dissolved in sufficient water to form a solution containing 10 percent of the salt. This solution should also have a temperature not in excess of 25 C. The solution of lead salt is added as rapidly as possible to the solution of azide, not more than a fen minutes being necessary. The lead azide which is immediately precipitated by this method is non-crystalline.

Non-crystalline lead azide is superior to crystalline lead azide with respect to use as a detonating compound for use in blasting caps, fuzes, etc. Although it has high intiating value, the non-crystalline form is not dangerous because of great sensitivity; and so can be washed, dried, and pressed without danger of explosion due to the fracture of a large crystal. For this reason it is preferable to use the non-crystalline form in blasting caps, detonators, ammunition fuzes, etc.

I claim 1. The method of preparing an explosive azide embodying, preparing an aqueous so- 9 lution containing 4% of sodium azide, maintaining it at a temperature not in excess of 25 C., while being agitated; adding rapidly to this'solution a slight excess of a suitable 2. The method of preparing an explosive azide embodying, forming an aqueous solution containing of sodium azide, maintaining the solution at a temperature not in excess of 25 C., forming an aqueous solution containing 10% of a metallic salt the metal of which is capable of reaction with the azide to form an explosive azide, and rapidly mixing the two solutions with a slight excess of the latter whereby a colloidal mass of azide is precipitated.

3. The method of preparing an explosive azide embodying, forming an aqueous solution containing &% of an azide, maintaining the solution at a temperature not in excess of 25 6., forming an aqueous solution containing 10% of a metallic salt the metal of which will react with the azide to form an explosive azide, and rapidly mixing the solution with a slight excess of the latter whereby a colloidal mass of azide will be precipitated.

l. The method of preparing an explosive azide embodying bringing together as rapidly as possible an aqueous solution containing 4% of an azide and an aqueous solution containing 10% of a salt of a metal capable of reacting with the azide to form an explosive while maintaining the solutions at a temperature not in excess of 25 C.

WILLIAM H. RINKENBACH. 

